So apparently it is true: Size does matter. In "Fat Pig," a fit, good-looking guy falls hard for a very overweight girl, and the attendant fuss among his judgmental friends and her sleeker rivals not only strains the bonds of love but also our notion of how wide a net we can cast for the person of our dreams.

The boorish title is a bit misleading. The 2004 play by Neil LaBute, author of "The Shape of Things," is a surprisingly gentle portrait of the pressures exerted on unconventional love, of the power those deemed attractive hold over people of less streamlined allure. Although the heart might want what it wants, it has to submit in "Fat Pig" to a jury of the appearance-obsessed. And their verdict is: Gimme svelter.

If the bitter conclusion to "Fat Pig" belies its romantic beginnings, the play, receiving its regional premiere at Studio Theatre, never strays far from engrossing. This is partly a function of LaBute's lacerating humor, brandished with especially entertaining effect in the office scenes among love-struck Tom (Tyler Pierce) and his dumbstruck colleagues, played to the callous hilt by Jason Odell Williams and Anne Bowles. The production's visual style is another important ingredient. Debra Booth's striking contemporary backdrops and Kate Turner-Walker's costumes add a cosmopolitan air to this darkening urban fairy tale, well directed by Paul Mullins.

At the consistently fascinating core of the production is Kate Debelack, who brings a wholly admirable, understated grace to Helen, the plus-size object of Tom's attentions. She is, like all of us, a bundle of contradictions, disarmingly self-possessed on some occasions and painfully self-denigrating on others. She has, for example, that nervous habit of remarking wryly on her own weight to temper the reactions of others.

The role requires skill and guts, as it calls on the actress to show a lot of flesh. Exposure, after all, is one of LaBute's themes. The relationship stalls as Tom cannot make the leap from private affair to public one; he's embarrassed to be seen with Helen. As much of the play is told from Tom's point of view, we're meant to share his discomfort.

As "Fat Pig" unfolds, however, more and more of our loyalty shifts to Helen. By the scene late in the play set at Tom's company beach party, in which Helen walks on in a bathing suit, an audience is thinking of Helen in a way fat people rarely are in American culture: as a sexual being. We're unsettled by the vulnerable position in which a woman can place herself through the simple act of baring her arms. If we look hard enough, the playwright seems to be saying, maybe we can learn to stop staring.

Body image is a national fixation, and a ubiquitous subject on Washington stages these days. In November, Horizons Theatre, specializing in women's topics, presented "The Body Project," a survey of female attitudes about their physiques. Later this month, "The Good Body," the latest work by Eve Ensler ("The Vagina Monologues"), arrives at the Lincoln Theatre.

When men take on the subject, the results are often cruder, more adolescent, as if better suited to "American Pie"-style treatment. This Stifleresque insensitivity is channeled in "Fat Pig" by Tom's office buddy, Carter. As portrayed by Williams, he's male arrogance incarnate, a jerk who is not beneath humiliating a friend in an effort to destroy Tom's relationship with a woman whom he looks upon as a lower form of life.

Williams exhibits a refined feel for despicability. His handling of the casual sabotage of a dinner date between Tom and Helen -- in a tricky scene nicely staged by Mullins -- is a swell example of social terrorism.

Bowles proves equally deft in the comic role of Jeannie, the slim blonde in accounting whom Tom throws over for Helen. One of the play's funnier moments belongs to Bowles: Appalled by Tom's choosing Helen over her, Jeannie cannot quite believe the subordinate role she's been assigned in his life, and so she lashes out at him risibly and ineffectively.

As Tom, Pierce is appealingly enigmatic. His anxious wavering, invested with an antic charm reminiscent of Ben Stiller, helps ensure there's some suspense as to whom Tom will satisfy -- Helen, or public opinion. Pierce's anguish ultimately unmasks not a reserve of compassion, but cowardice.

In his earlier play "The Shape of Things," presented by Studio three years ago, LaBute explored some of the same terrain, about our obsession with facets of people that are only skin deep. If there's any serious problem with "Fat Pig," it's one that it shares with the previous play: that it's difficult to derive anything truly profound out of an aspect of human nature so superficial.

No one will be stunned by how things turn out in "Fat Pig." And yet, we all feel a little bit better for having been given the chance to root for Helen.